In recent years, cells cultured by cell culture techniques have been used for drug efficacy tests and drug toxicity tests. However, cells cultured by the conventional culture techniques extend two-dimensionally and have a shape that is significantly different from that in vivo. This poses a problem that the cells do not have their original cell functions, which makes it difficult to reflect the behavior of drugs in vivo.
Under such circumstances, a spheroid culture method for simulating the morphology of tissues in vivo has attracted attention in recent years. For example, a method is disclosed in which the bottom surface of a 96-multiwell plate is formed into a funnel shape and a single spheroid is formed therein (Patent Literature 1). Other examples of the spheroid culture method include a technique in which a fine honeycomb structure is formed in a culture bottom surface to reduce the adhesion properties of cells with respect to material, thereby forming spheroids (Patent Literature 2), and a method using an exogenous cell aggregation agent (Patent Literature 3).